Camshaft phasers for varying the phase relationship between the crankshaft and a camshaft of an internal combustion engine are well known. A prior art vane-type phaser generally includes a plurality of outwardly-extending vanes on a rotor interspersed with a plurality of inwardly-extending lobes on a stator, thereby forming alternate advance and retard chambers between the vanes and lobes. Engine oil is supplied via a multiport oil control valve, in accordance with an engine control module, to either the advance or retard chambers as required to meet current or anticipated engine operating conditions.
It is also well known to provide prior art cam phasers with an intermediate locking pin and seat for locking the camshaft phaser at a position intermediate of its full advance and retard positions. See for example, US Patent Application Publication No. 2007/0277757 which was published Dec. 6, 2007, the disclosure of which is expressly incorporated herein by reference. Such prior art intermediate locking pins and seats are known to have circular cross-sectional shapes. A known disadvantage to using locking pins and seats with circular cross-sectional shapes is the high level of precision to which the locking pin and seat must be manufactured in order to allow the locking pin to slide freely into the seat while maintaining an acceptable amount of lash between the rotor and stator when the locking pin is engaged with the seat. Manufacturing the locking pin and seat to such a high level of precision can be cost prohibitive. If a lesser degree of precision is used to manufacture the locking pin and seat, the locking pin may not move freely into and out of the seat, or there will be an excessive amount of lash between the rotor and stator which can cause objectionable noise as well as durability issues.
What is needed is a camshaft phaser with an intermediate locking pin and seat that require less precision to manufacture, and yet is durable and operates properly and quietly. Therefore, it is a principal object of the present invention to provide a locking pin and seat for a camshaft phaser that requires less precision to manufacture while allowing the locking pin to move freely into the seat and maintain an acceptable level of lash between the rotor and stator.